Moisture determination



y 6 H. E. ALQUIST ETAL 3,196,667

MOISTURE DETERMINATION Filed 001;. 31. 1960 PPM WATER N U h I T I 0 1 l 1 I l 20 4o IMIN. 20 4o 2MlN. 2o 40 -3MlN.

TESTER FREEZING TIME 12 p20 Q FIG.

' 3s 1- 4| I. as 22 37 24 34 V F IGIZ g; 29 4a INVENTORS L- H.E.ALQUIST g by D.E. SMITH 3| 32 M 45 A TTORNEYS a assess? lc Patented July 27, 1

3,196,667 MGETURE DETERMlNATlGN Henry E. Alquist and Dan E. Smith, Bartlesville, G lda assiguors to Phillips Petroleum (Ionipany, a corporation of Delaware Filed Oct. 31, 196i), Ser. No. 66,164 (Ilaims. (Cl. 73-53) This invention relates to the determination of the moisture content of fluids. In one aspect, this invention relates to an apparatus for determining the moisture con tent of a fluid, comprising snap acting means for changing from one to another of two flow restricters in a flow passage. In another aspect, this invention relates to a moisture tester comprising a flow passage and means to change from one flow restriction to another. In another aspect, this invention relates to a method for determining the moisture content of a fluid by flowing the fluid through a restriction to cool the testing zone and then flowing the fluid through a smaller opening and determining the time required for a shut-oil due to freezing of the contained moisture.

Knowledge of the moisture content of various fluids often is an important consideration. For example, condensed moisture may interfere with the flow of gas in a pipe line and, under certain conditions of temperature and pressure, moisture may combine with a gaseous hydrocarbon to form gas hydrates. The solid product thus formed may collect in suflicient quantity to reduce the flow rate or even to plug completely the pipe line in which the flow is occurring. The specifications under which liquefied petroleum gases are sold often include the moisture content. Our invention is particularly suited for determining the moisture content of liquefied petroleum gas (LPG) hydrocarbons without resorting to laboratory analysis. The method and apparatus of our invention may be used by comparatively unskilled labor under conditions existing in commercial operations with accuracy suflicient to determine whether specific examples meet moisture specifications.

It is an object of this invention to provide a method and apparatus for determining the moisture content of fluids. Another object of this invention is to provide a method and apparatus suitable for determining fluid moisture content under conditions of field operations. Another object of this invention is to provide a method and means for determining moisture content of fluids with which reproducible determinations can be made.

Other aspects, objects and the several advantages of this invention will be apparent from a study of this disclosure, the drawing and the appended claims.

The apparatus according to our invention comprises a body having a flow passage therethrough and means to provide a relatively mild restriction to flow and a relatively severe restriction to flow at will. The restrictions to flow may be provided by a flow restricting memher, a portion of which is provided with two different flow restricting portions which may be inserted into the flow passage. Also, according to our invention, there is provided a flow restricting and positioning portion outside the flow passage, as well as the two portions which are inserted into the flow passage. Further, according to our invention, there are provided a moisture tester having a flow passage and a flow restricting member, the combination of which provides means for obtaining reproducible test results. Also, according to our invention, there is provided a method of determining the moisture content of a fluid by flowing the fluid through a esting zone having a restricted flow passage to cause expansion of the fluid and resulting cooling of the zone and further restricting the flow passage and determining the time required for the flow passage to plug due to freezing of contained moisture.

In the drawing, FIGURE 1 illustrates a combination of elements useful in determining the moisture content of a fluid. FIGURE 2 is a vertical cross section of a moisture tester, according to our invention. FIGURE 3 illustrates the flow control member of the moisture tester. FIGURE 4 is a graph showing the relationship between moisture content and tests made according to the present invention.

In FIGURE 1, a source of liquefied petroleum gas (LPG) it) is connected through a valve 11 and a pressure regulator 12 to moisture tester 20.

As shown in FIGURE 2, moisture tester 2th comprises a body 21, control housing 22, flow control member 23, spring 24, and cam lever 25. Body 21 is provided with inlet passage 26, outlet passage 27 and vertical flow passage 23. At the top of flow passage 28, there is provided a circular lip 2? having a substantially planar upper surface 39. Body 21 is also provided with threaded connections 31, 32 and 33 which connect with an inlet pipe, an outlet pipe and with control housing 22, respectively,

Control housing 22 connects with body 21 by threads 33, thereby providing a fluid-tight seal therewith. There are also provided a cylinder 34- and a coaxial bore 35 through which flow control member 23 extends. As illustrated, spring 2 also extends upward within cylinder 34 and there are provided an O-ring seal 36 and a sealing washer 3'7 in the upper portion of cylinder 34 to prevent leakage of fluid through bore 35.

Cam lever 25 comprises a handle portion 38, a recess 39 and cam surface 45). Lever 25 is attached to the upwardly extending stem 41 of control member 23 by a pin 41a.

Referring now to FIGURE 3, as well as to FIGURE 2, flow control member 23 comprises stem 41, seat 42, a first cylindrical portion 43, a second, smaller diameter, cylindrical portion 44 and a portion 45 having parallel planar sides 46 and 47 and arcuate sides 48 and i9. Seat 4-2 has a first substantially planar area 50 at right angles to the axis of the member 23, area 5%) being provided with relieved portionsSl and 52.

With the various elements in the position illustrated in FIGURE 2, area 59 contacts a portion of the surface 3t! of lip 29 to position flow control member 23 relative thereto. In this position, the portions 43, 44, and 45 are all inside flow passage 28 and the restriction to flow ofa fluid through this passage is the sum of the restriction provided by portions 43, 4-4 and 45, plus the restriction provided by the clearance between relieved areas 51 and 52 through which the fluid must flow to reach outlet passage 27. Member 23 is urged to this position and there maintained by spring 24 when lever 25 is placed in the position shown in FIGURE 2. When cam lever 25 is rotated about pin 41a in the direction of the-arrow, cam surface 46 engages the upper portion of control housing 22 and, as lever 25 is moved farther in the direction of the arrow, a force is exerted due to the cam action to raise member 23 a distance equal to the difference in the height of pin 41a from the upper surface of housing 22 and the distance from pin 41a to the cam surface 40 at right angles to a flat portion of cam surface 46 which is vertical in the position illustrated in FIGURE 2 but which is horizontal When lever 25 reaches the extreme of movement in the direction of the arrow, at which time this flat surface cooperates with the upper surface of housing 22. to provide a stable position for lever 25 and, therefore, for the entire movable assembly. This assembly obviously is stable in the position illustrated in FIGURE 2 as well. With lever 25 rotated to the position in which flow control member 2-3 is lifted vertically areas-e7 in FIGURE 2, area St) is, of course, lifted from surface 3i! and portion 433 is withdrawn from passage 28 while portion 45 remains therein, the position preferably being one in which portion 434 is positioned opposite surface 34 of lip 29 In operation, when it is desired to determine the moisture content of the fluid in source It}, lever 25 is rotated to raise member 23, as described above, and valve 111 is opened, allowing the fluid t0 flow through tester 2d. Portion 45 of flow control member 23 provides a restriction in flow passage 28 which causes a pressure drop through this area and, thus, an expansion of the fluid and consequent cooling of the body 21. When suflicient cooling has been accomplished, the lever 25 is flipped into the position illustrated in FIGURE 2, thus, providing a much greater restriction to flow through passage 28, an increased pressure drop and resulting increased expansion of the fluid and the resulting increased cooling effect. This increased cooling efiect, in combination with the very small available flow area in passage 28, results in plugging of this area with ice or hydrates. At the time lever 25 is moved into the position shown in FIGURE 2, a stopwatch is started and the time determined to the time of shutoff due to plugging. This time is a function of the moisture content of the fluid flowing through the apparatus.

In one embodiment, flow passage 23 is finished to a diameter of between .1285 and .1286 inch. The diameter of portion 43 is between .1280 and .1281 inch and the diameter of portion 44 is between .103 and .105 inch. The depth of the relief of portions 51 and 52 is between .005 and .007 inch, portion 43 is from .085 to .087 inch long and portion 44 between .046 and .056 inch long and the total length of elements 43, 4d and 4-5 combined is between .194 and .196 inch.

In a test using a moisture tester having the dimensions set out above, a series of six samples was obtained from a stream from a propane dehydrator, the six samples corresponding with six runs made to determine the freeze time with the moisture tester described. The results of the tests are given in Table I and are plotted in the chart of FIGURE 4. This chart is a plot of moisture tester freezing time and the actual moisture content as determined by laboratory tests of the samples taken.

1 Moisture tester 2 was on the dehydrator outlet. 2 Moisture tester 1 was on the dehydrator inlet.

Reasonable variation and modification are possible within the scope of the foregoing disclosure, the drawing and the appended claims to the invention the essence of which is a moisture tester comprising a flow passage and a flow control member cooperating therewith to provide more than one degree of flow restriction through the passage and a method of determining the moisture content of a iiuid by flowing the fluid through a zone, providing a first restriction to flow which results in cooling of the zone, providing a second flow restriction which results in freezing and plugging in the zone and determining the time required for such plugging. 7

We claim:

1. The method of determining the moisture content of a fluid under pressure which comprises flowing said fluid through a testing zone while maintaining a restricted passage therein, thus causing expansion of aid fluid and resultant cooling of said zone, further restricting said flow passage and determining the time required to cause said flow passage to close due to freezing of moisture therein.

2. The method of determining the moisture content of a fluid under pressure which comprises opening a restricted flow passage for said fluid through a testing zone, flowing said fluid through said passage to cool said zone, partially closing said flow passage thereby further restricting how of said fluid through said zone, continuing to flow said fluid through said zone until said fluid passage is closed due'to freezing of moisture from said fluid, and determining the time required to produce the closure of said passage.

3. The method of claim 2 wherein said fluid is a liquefied petroleum gas.

4. The method of determining the amount of moisture present in a iiuid under pressure'which comprises opening a first restricted flow passage through a testing zone, flowing said iiuid through said first passage whereby said fluid expands and cools said zone, at least partially closing said first restricted flow passage thereby providinga second restricted flow passage for said fluid through said zone, flowing said fluid through said second passage until said passage is closed due to freezing of moisture from said fluid, and determining the time required to cause said second passage to close.

5. The method of claim 4 wherein said fluid is aliquefied petroleum gas.

References Cited lay the Examiner UNITED STATES PATENTS 1,980,752 11/34 Eskilson et al. 13840 2,145,203 1/39 Walker et a1. 73-53 2,391,586 12/45 Miller 13840 2,449,352 9/48 White 62-52 2,571,470 10/51 Milligan 73-53 2,591,084 4/52 Martin 73-17 2,705,420 4/55 Bryan et al 73-53 RICHARD C. QUEISSER, Primary Examiner.

CHARLES A. CUTTING, DAVID SCHONBERG,

Examiners. 

1. THE METHOD OF DETERMINING THE MOISTURE CONTENT OF A FLUID UNDER PRESSURE WHICH COMPRISES FLOWING SAID FLUID THROUGH A TESTING ZONE WHILE MAINTAINING A RESTRICTED PASSAGE THEREIN, THUS CAUSING EXPANSION OF SAID FLUID AND RESULTANT COOLING OF SAID ZONE, FURTHER RESTRICTING SAID FLOW PASSAGE AND DETERMINING THE TIME REQUIRED TO CAUSE SAID FLOW PASSAGE TO CLOSE DUE TO FREEZING OF MOISTURE THEREIN. 